Radios, stereo systems and tape decks have become more and more sophisticated to deliver higher quality sound to the listener. Such systems have also become more and more expensive. During the past several years, such systems have become a common target for burglers. The usual car or truck unit is attached at the tuner and volume shafts to a plate attached to the vehicle, oftentimes the dashplate of the vehicle. Commonly, the shafts protrude through openings in the plate and a nut is tightened on a threaded portion of each of the shafts to draw the chassis of the electronics to the rear side of the plate. One or more knobs is fastened with a set screw to the shafts. Once the burgler has obtained entry into the vehicle, it has been a relatively simple task for him to remove the knobs, loosen the nuts, cut or remove any wires attached between the vehicle and the chassis of the electronics, and than remove the electronics.
Many people have recognized the problem of defeating the would-be burgler, but the solutions have been inadequate. For example, U.S. Pat. No. 3,358,480, shows a locking mechanism which fits over the knobs attached to the shafts. The mechanism is comprised of a mounting nut which threads onto each of the shafts of the electronics unit. The mounting nut is screwed to the dashplate. The mounting nut includes a plurality of slots. A cylindrical housing fits over the knob and shaft of the electronics unit and has tangs for fitting into the slots. The housing makes the screws which attach the nut to the dashplate inaccessible. A regular key and lock assembly controls the tangs for installation and removal of the housing to the slotted nut. The problem with the locking mechanism is that the user must always install and remove the housing portion of the mechanism. The key may get lost. The bigger problem, however, is that it is simply too inconvenient for the average user to continually have to worry about installing and removing the housing. U.S. Pat. No. 3,766,759, shows a somewhat different locking device wherein a threaded shaft extends completely through the housing of the electronics unit. The shaft is lockable within the housing to prevent rotation of the shaft. The locking mechanism is apparently accessible only from underneath or behind the electronics unit. The problem with this locking device is that retrofitting an existing electronics unit is next to impossible since appropriate holes must be drilled through the entire unit and a threaded bushing installed. The device appears to be practical only if it is designed into the electronics unit.